public class ReplaceCheck
{
   /**
      A method to replace letters as follows:
      the letter e becomes 3, the letter i becomes 1,
      the letter l becomes 7, and the letter o becomes 0.
      @param str a string
      @return the string with the characters replaced
   */
   public static String replace(String str)
   {
      String x = "";
      for(int i=0;i<str.length();i++)
      {
         char a = str.charAt(i);
         if(str.charAt(i)=='e')
            x = x + '3';
         else if(str.charAt(i)=='i')
            x = x + '1';
         else if(str.charAt(i)=='l')
            x = x + '7';
         else if(str.charAt(i)=='o')
            x = x + '0';
         else
            x = x + a;
      }
      return x;
   }
}